Ian is diving into the depths of the Ether Sea.
The so-called Ether Sea, to put it simply, is the 'past and future' and 'parallel universes' of 'this space-time,' much like how Ian can observe the circumstances of other Dao Paths using the Foresight View, which is actually Ian peering into the direction of a branch of the Ether Sea, seeing the scenery on the other side of the ocean.
And after becoming a 'Demi-Star God,' Ian certainly cannot truly transcend time and space, 'crossing physically' into those parallel universes, but having abandoned all physical form, he can still observe the conditions of numerous parallel universes.
In simple terms, Ian can now observe any kind of Dao Path at any time, and infinitely continue observing—as long as he has a causal connection with that Dao Path, just as he must have truly encountered the Worm Nest to be able to observe those infinite Dao Paths of the Swarm.
